DE10228343B3 - Process for the production of a liquid fertilizer or low salt substrate from compost - Google Patents

Abstract

The invention relates to a process for the preparation of a solution enriched with nutrients and humic substances, e.g. B. as a basis for the production of plant fertilizers. At the same time, this invention relates to a method for producing a desalted substrate compost from standard composts, e.g. B. for the production of culture substrates.

Description

1. Field of application

The invention relates to a method to produce a liquid fertilizer Compost, especially using a membrane process, and to produce a low-salt compost.

II. Technical background

The use of composts on a scale of more than 20 vol .-% for the production of culture substrates fails usually due to the excessive nutrients Salt levels of the composts. It follows that large quantities still exist of peat flow into the substrate production.

This is questionable from an ecological point of view because peat is a finite resource. It was the use of German cakes largely restricted, this led but only to the fact that the need by import cake from countries with a less restrictive environmental policy is covered.

These critical nutrient and salinity of the standard composts are only when growing plants undesirable and can therefore to a later one Time can be added to the culture again as part of the necessary fertilization measures. It is therefore advantageous to use composts by removing nutrients and salt to make it more suitable in the substrate area (use> 20% by volume). The guiding principle here is that the nutrient and salt content extracted from the compost is one base enriched with humine for the in the course of the continuous top dressing required fertilizers forms.

From the publication JP 102 36 894 A a method is known in which a liquid fertilizer is produced by vigorously stirring and aerating organic waste with water and by decomposing and dissolving or suspending the organic waste by aerobic microorganisms. However, the aerobically fermented waste in suspended form is part of the liquid fertilizer.

Another method for working up organic material is in the document DE 196 00 711 A1 described. Before aerobic decomposition, the material is extracted by spraying with water and the liquid collected is then anaerobically decomposed.

a) Technical task

It is therefore the object according to the invention a process for the production of liquid fertilizers with high humic content on the one hand and from a substrate raw material on the other. basis therefor are the points mentioned in II.

b) solving the problem

This task is characterized by the Features of claim 1 solved. Advantageous embodiments result from the subclaims.

The method according to the invention is based on that the nutrients be removed from the compost by washing (elution). there the compost as a raw material is initially mixed with a liquid added and the resulting mixture mixed. Thereupon the Mix a certain part of its liquid content, the eluate or the raw liquid fertilizer, again withdrawn. This raw liquid fertilizer, in which is now part of the original nutrients contained in the compost solved is then further treated.

The rest of the batch can be after Withdrawal of the eluate again mixed with a liquid and mixed , whereupon an eluate is withdrawn and treated as a liquid fertilizer becomes. This washing step can be performed as often as required be repeated to give the raw liquid fertilizer preferably huge Share of the nutrients in the compost.

As a liquid to be added can be any organic or inorganic solvent, for example water, a mixture of water and any Acid or Water and any lye, a concentrated acid or a concentrated lye. As acids can be here for example, but not in the final list, nitric acid or sulfuric acid in various Concentration levels can be used. At the possibly used Water can be tap water, distilled water, process water or water that is recovered in a further process step will act.

The compost or residual batch added at the beginning of the corresponding washout process liquid can be varied for the individual wash-out processes. For example the initial compost can be washed out with a Mixture of water and an acid be moved while the possibly following ones further washings as a liquid to be added Water is used.

The amount of fluid that is out gang compost is supplied at the beginning of the first washing process depends essentially on the nature of the starting compost, in particular its inherent liquid content, that is, its moisture. The mass ratio between the starting compost and the amount of liquid supplied at the start of the first washing process is preferably in the range from 1: 2 to 2: 1, preferably between 1: 1.5 and 1.5: 1 and particularly preferably between 0.95 and 1 , 05th

The amount of liquid that the remaining batch after the eluate has been withdrawn at the beginning of each further washout is essentially dependent on how much eluate in the form of raw liquid fertilizer Batch was removed in the previous liquid withdrawal. This amount of fluid can for every single washout may be different. In particular the original compost at the start of the first wash amount of liquid added from the amounts of liquid added in the further wash-out processes differ. For example, the dewatered compost after the first dewatering step one opposite the original compost have different moisture content. For the Case that for every washout has an even ratio between liquid and solids in the batch is required accordingly correspondingly less liquid in the further wash-out steps be added. The elution capacity can also be changed the added liquid change in the individual washing steps, so that possibly also it may be necessary to adjust the amount of liquid added can.

Anyone can mix the mixture any method can be used by which an even mixing with high mix throughputs, resp. short dwell times and gentle treatment of the mix, is achieved. It can both mechanical mixing methods, such as centrifugal and Whirling, stirring or circulation processes, as well as thermal, for example convection-based, mixing methods are used. The mixing process can be both discontinuous as well as run continuously.

After each mixing according to the invention Eluate withdrawn. This withdrawal can be done in a variety of ways. In addition to the preferably used pressing of the batch would also be a use of centrifugal forces with a centrifugal arrangement for separating the eluate from the Batch conceivable. Squeezing the batch can, for example by a baler or by a belt press. The one to drain on the batch exercised Pressure hangs in this case of the desired one freeness of the batch and can for the different washouts vary quite a bit. For the one you want freeness can for example factors such as changing elution capacity the respectively added liquid or changes the surface conditions play a role in the compost by mixing. As a result, could for example, the pressure increased from washout to washout or alternatively only during of the last washout can be increased.

According to the invention, the eluates of the individual Stages are either combined into a common liquid fertilizer or processed in separate lines to different products.

The after washing out or the washouts Washed out compost can then be lost due to its reduced nutrient and Salinity can be used to produce growing media.

In a further process step according to the invention, the solids content of the raw liquid fertilizer obtained by washing out. This can by pure sedimentation, but is preferred a flocculation stage upstream, in which there is in the raw liquid fertilizer Suspended substances, particles and humic substances by adding flocculants be flocculated. Iron nitrate is the preferred flocculant in combination with KOH solution (20%) and an anionic, organic flocculant polymer, however, other flocculants, such as chloride-free, are also Iron (III) salts are conceivable. Cutting off the flakes is next to the method sedimentation is also possible by flotation. A decrease in Solid content of the raw liquid fertilizer can alternatively and / or additionally also done by means of filters.

A mechanical is also alternative / supplementary Solids separation (e.g. by means of a decanter or one based on centrifugation based method) subject of the extension.

In addition, the separated Sediment or flotate are dewatered in a further step, the liquid withdrawn from the raw liquid fertilizer to be processed is supplied.

After the raw liquid fertilizer largely from its solids was liberated takes place in a further process step according to the invention a concentration of the raw liquid fertilizer.

In this step the raw liquid fertilizer becomes a Part of its solvent withdrawn so that the concentration of the solutes is increased. Preferably a membrane process is used for this, but they are also other options conceivable for concentration, for example by distillation.

When using a membrane process the raw liquid fertilizer is divided into a permeate which can penetrate the membrane and essentially consists of the solvent used, and a retentate which cannot penetrate the membrane. By removing the solvent, the retentate is a version of the raw liquid fertilizer fed to the membrane process that is concentrated with regard to the dissolved ingredients.

The concentration of the raw liquid fertilizer can comprise several, preferably two stages, in each of which the Retentate and / or the permeate from the previous concentration step is subjected to a further concentration. The separated one Part of the solvent can, if necessary after further dilution, to be added in one of the wash-out processes liquid be used.

The different levels of concentration can rely on various methods, but are preferred Concentration levels used based on membrane processes in the course of which the respective retentate and / or permeate of a run Stage is supplied to a further subsequent stage. In the membrane process according to the invention can any type of membrane can be used, but is preferred Nano-filtration membranes and reverse osmosis membranes are used.

In the different stages of the membrane process can both identical and different membranes used become.

In a preferred embodiment the concentration takes place in a two-stage membrane process, the first separation step based on the principle of nano-filtration and the second separation step is based on the principle of reverse osmosis and wherein the permeate of the first separation stage of the second separation stage supplied becomes.

To the concentrated nutrient content Raw liquid fertilizer regarding adapt to the requirements when used as a high-quality special liquid fertilizer, can be used as a further method step according to the invention a so-called conditioning. This is it a process in which a plant-physiologically favorable relationship between phosphorus, potassium and nitrogen e.g. B. by the addition of chemicals or organic nutrient carriers.

c) working examples

• 1 ein Schema eines erfindungsgemäßen Verfahrens und
• 2 ein Schema eines erfindungsgemäßen Aufkonzentrierungsverfahren.

An embodiment according to the invention is described in more detail below using the figures as an example. Show it:

• 1 a diagram of a method according to the invention and
• 2 a schematic of a concentration process according to the invention.

In 1 a preferred embodiment of the method according to the invention is shown.

As a result, the compost 1 first in a first wash-out step with a liquid mixture 2 from fresh water and concentrated nitric acid. The addition of nitric acid causes carbonates to be driven out. The mixing ratio of the fresh water and the nitric acid in the present case is 0.1 l HNO _{3, conc.} per cubic meter of water up to 1 l HNO _{3, k o nz.} per cubic meter of water, in particular 0.35 l HNO _{3, conc.} per cubic meter of water. The mass ratio of compost 1 and liquid mixture 2 in the first wash step depends on the inherent moisture content of the compost 1 and in the present case it is preferably 1: 1.

The resulting mixture is then mixed, in the present case using a commercially available ploughshare mixer 3 , Such a system, which works according to a centrifugal and whirling process, is characterized by intensive mixing of the entire mix, even with high mix throughputs or short dwell times, and by gentle treatment of the mix.

In the subsequent process step, according to the invention, the raw liquid fertilizer is added to the batch 4 taken in the form of the eluate. In the preferred embodiment, this is done by means of a belt press 5 , in which the batch to be dewatered is passed through a roller arrangement between two sieve belts in circulation.

The drained compost 6 after the first wash-out step two more times with a liquid mixture 2 , this time only consisting of water without the addition of acid, mixed, mixed and squeezed out before it becomes an eluted compost 7 no longer participates in the further process and can be further processed into cultural substrates. The eluate obtained in the individual wash-out steps is combined and the further process as raw liquid fertilizer 4 fed.

This raw liquid fertilizer 4 is freed as completely as possible of its suspended matter, particles and humic substances by a combined flocculation / precipitation stage 8 or 9. First of all, the raw liquid fertilizer 4 a flocculant and a precipitant with stirring 10 respectively. 11 added. In the present case, it is the flocculant 10 to iron nitrate solution (34%). To adjust the pH value required for flocculation, KOH solution can be added, for example. With constant stirring, it is then used as a precipitant 11 a commercially available anionic, organic flocculation polymer (0.1%) was added before the Flo was done.

As previously mentioned, the flakes can alternatively also be separated by means of flotation. The sediment sludge 12 is in a device 12 ' dewatered, the filtrate 13 ' the raw liquid fertilizer freed from solids 14 is fed and the remaining filter cake 13 either the eluted compost 7 is supplied or as an encore 26 can be used for fertilizers. The raw liquid fertilizer freed from solids 14 can then add another filter level 15 , such as a sand filter, before being subjected to call concentration 16 is fed.

The process step of concentration according to the invention 16 is carried out in the embodiment of the invention presented here by means of a membrane method. This two-stage membrane process in the present case, consisting of nanofiltration 17 and a downstream reverse osmosis 18 is detailed in 2 shown.

As a result, the raw liquid fertilizer is freed from solids 14 through the first membrane based on the principle of nano-filtration 17 ' the permeate1 19 deposited, whereby the concentrated retentate 1 20 arises. Usually a 1: 9 separation can be achieved here, i.e. 9/10 that of the membrane 17 ' supplied raw liquid fertilizer freed from solids 14 the membrane 17 ' as permeate1 19 pass.

How continue from 2 can be seen, the permeate1 obtained in the first step 17 of the membrane process 19 a second membrane 18 ' , which in this case is based on the principle of reverse osmosis. The retentate 2 retained in this second step 18 of the membrane process 21 with the retentate 1 obtained from the first step 17 of the membrane procedure 20 merged and forms the concentrated raw liquid fertilizer 24 , That is the second membrane 18 ' Penetrating Penneat2 22 can, like from 1 can be seen to be attributed to the process by using it as part of the compost 1 liquid mixture to be transferred is used.

The concentrated raw liquid fertilizer obtained as the starting product of the concentration 24 can, depending on its chemical composition, in a further process step 23 be conditioned by adding chemicals. This conditioning can consist, for example, of adapting to the nutrient conditions of a high-quality special liquid fertilizer. However, the chemical composition can also be changed here with regard to plant compatibility, environmental suitability or the like.

If the nutrient ratios are adjusted, the ratio of phosphorus, potassium and nitrogen can be adjusted to the desired value by adding (NH ₄ ) H ₂ PO ₄ , KNO ₃ and / or NH ₄ NO ₃ .

Finally, the liquid fertilizer lies as a result of the method according to the invention 25 and desalted compost 7 in front.

1

compost

2

liquid mixture

3

Plowshare mixer

4

Rohflüssigdünger

5

belt filter press

6

dehydrated compost

7

eluted compost

8th

flocculation

9

precipitation stage

10

flocculants

11

precipitant

12

sediment sludge

12 '

dehydrator

13

filter cake

13 '

filtrate

14

Of Solids-free raw liquid fertilizer

15

filter stage

16

concentration

17

nanofiltration

17 '

Nanofiltration membrane

18

Reverse osmosis

18 '

Reverse osmosis membrane

19

Permeat1

20

Retentat1

21

Retentat2

22

Permeat2

23

conditioning

24

Rufkonzentrierter Rohflüssigdünger

25

liquid fertilizer

26

encore for fertilizers

Claims (33)

Process for processing compost ( 1 ), characterized in that for the production of a nutrient-poor substrate ( 7 ) or a raw liquid fertilizer ( 4 ) from compost a) the compost to be treated ( 1 ) with a liquid ( 2 ) is added to create a mixture, b) the mixture is mixed mechanically, c) liquid is extracted from the mixture, which represents the raw liquid fertilizer, while the solid part of the mixture remaining after the withdrawal of the raw liquid fertilizer removes the nutrient-poor substrate ( 7 ) represents Process for processing compost ( 1 ) according to claim 1, characterized in that for the production of a liquid fertilizer from compost as a further process step d) the solids content of the raw liquid fertilizer ( 4 ) is reduced. Process for processing compost ( 1 ) according to claim 1 or 2, characterized in that for the production of a liquid fertilizer from compost as a further process step e) a concentration of the raw liquid fertilizer ( 4 ) he follows. Method according to one of the preceding claims, characterized in that the liquid ( 2 ) is a mixture of liquids. A method according to claim 3 or 4, characterized in that during the concentration of the raw liquid fertilizer separated water back to the system as part of the liquid added in process step a) ( 2 ) is supplied. Method according to one of claims 3 to 5, characterized in that that the concentration process is a combination of there are at least two separation steps. Method according to one of claims 3 to 6, characterized in that the concentration of the raw liquid fertilizer ( 4 ) in process step e) by evaporation. Method according to one of claims 3 to 6, characterized in that the concentration of the raw liquid fertilizer ( 4 ) in process step e) by distillation. Method according to one of claims 3 to 6, characterized in that the concentration of the raw liquid fertilizer ( 4 ) in process step e) by a membrane process. A method according to claim 9, characterized in that the Membrane process from a combination of at least two separation steps exists, which are based on the principle of reverse osmosis. Method according to claim 9 , characterized in that the membrane process consists of a combination of at least two separation steps which are based on the principle of nano-filtration. A method according to claim 9, characterized in that the Membrane process from a combination of at least two separation steps exists, the individual separation steps the principles of reverse osmosis and nano-filtration. A method according to claim 9, characterized in that the Membrane process from a combination of at least two separation steps consists, the first separation step on the principle of nano-filtration based. Method according to one of claims 9 to 13, characterized in that the permeate obtained in the concentration by a membrane process ( 22 ) the system again as part of the liquid added in process step a) ( 2 ) is supplied. Method according to one of claims 3 to 13, characterized in that, in addition, as the last process step, the ratio between different nutrients in the concentrated raw liquid fertilizer ( 24 ) is set to a plant physiologically favorable value. A method according to claim 15, characterized in that it yourself with the nutrients are those from the group of phosphorus, potassium and nitrogen. A method according to claim 15 or 16, characterized in that that the setting is made by adding chemicals. A method according to claim 15 or 16, characterized in that that the adjustment is made by adding organic nutrients. Method according to one of the preceding claims, characterized in that steps a), b) and c) are repeated as often as required and the raw liquid fertilizer (step c} extracted from the batch) 4 ) further process steps are fed together. Method according to one of the preceding claims, characterized in that steps a), b) and c) are repeated as often as desired and the raw liquid fertilizer extracted from the batch in step c) ( 4 ) further process steps are fed separately. Method according to one of the preceding claims, characterized in that the mass ratio between the compost ( 1 ) and the liquid added under a) ( 2 ) is in the range of 1: 2 - 2: 1. Method according to one of the preceding claims, characterized in that the mass ratio between the compost ( 1 ) and the liquid added under a) ( 2 ) is in the range of 1: 1.5 - 1.5: 1. Method according to one of the preceding claims, characterized in that the mass ratio between the compost ( 1 ) and the liquid added under a) ( 2 ) is in the range of 0.95 - 1.05. Method according to one of the preceding Claims, characterized in that the liquid (2) added when process step a) is run through for the first time consists of a mixture of water and an acid, but is repeated as a liquid when step a) is repeated ( 2 ) Water is added. A method according to claim 24, characterized in that as Acid used nitric acid becomes. Method according to one of claims 2 to 25, characterized in that the reduction in the solids content of the raw liquid fertilizer mentioned in process step d) ( 4 ) by d1) flocculation and d2) separation of the flocculated components. A method according to claim 26, characterized in that the in process step d2) separation of the flocculated Components are made by sedimentation. A method according to claim 26, characterized in that the in process step d2) separation of the flocculated Components are made by flotation. Method according to one of claims 2 to 25, characterized in that the reduction in the solids content of the raw liquid fertilizer mentioned in process step d) ( 4 ) by centrifugation. Method according to one of claims 2 to 25, characterized in that the reduction in the solids content of the raw liquid fertilizer mentioned in process step d) ( 4 ) by using at least one decanter. Method according to one of the preceding claims, characterized in that that the liquid withdrawal mentioned in process step c) by pressing he follows. A method according to claim 31, characterized in that for Pressing a baler is used. A method according to claim 31, characterized in that for Pressing a belt press is used.